Deer hunter set up equipment (6)
I believe the answer is:
tackle
'equipment' is the definition.
(tackle is a kind of equipment)
'deer hunter set up' is the wordplay.
'deer' becomes 'elk' (type of deer).
'hunter set' becomes 'cat' (I can't justify this - if you can you should believe this answer much more).
'up' says the letters should be written backwards (in down clue: letters go upwards).
'elk'+'cat'='elkcat'
'elkcat' backwards is 'TACKLE'.
Can you help me to learn more?
(Other definitions for tackle that I've seen before include "Confront" , "A rugby interception" , "Try to deal with fishing gear" , "Take hold" , "Compete for ball" .)